Umphrey’s McGee is a big believer in crowd participation. But it goes a bit further than urging the audience to sing along from time to time.

The Chicago-based jam band has maintained a sense of upward mobility through 15 years of steady touring, in no small part aided by creative efforts to engage its fanbase in unusual ways. It’s one thing to take song requests via Twitter — it’s quite another to play an entire “choose your own adventure” set, in which audience members use their phones to vote for different choices on a song-by-song basis.

“People really enjoy having that ability to influence a piece of music that’s happening, and we’ve figured out ways to improvise where we’re taking risks but there are less and less times when we fall on our face,” says keyboardist Joel Cummins, on the phone from the road. “It’s not the band being up on top of the mountain and occasionally coming down and dropping some truth among the fans and going back up. That’s how things went in the 1970s and 1980s, but we’re in a different era at this point. Fans want to have that interaction.”

In-show fan voting is a rare thing, but a hallmark of the band’s annual four-set extravaganza called “UMBowl,” a Super Bowl of live rock music with each set devoted to a concept. Last year’s event included a set for which fans were invited to tweet descriptions of proposed jams — phrases like “warrior marching into battle” and “simply ambient bliss” — which the band then emulated.

Umphrey’s McGee plays the Bank of America Pavilion on Saturday, in a co-bill with STS9. Each band will play one long set, and cross-pollination is expected.

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UMPHREY’S McGEE

Stylistically, Umphrey’s McGee draws on a stew familiar from other bands in the scene, including heavy helpings of classic rock and a tinge of electronica. But it goes heavier on the prog-rock element, with flashes of metal. For years, it was seen as perhaps the promising upstart. Now it’s been around long enough to author its own legacy.

“Ten years ago a lot of people were labeling us as heirs to the throne of Phish, but that’s not something we were ever trying to be. I really enjoy that band’s music and I have a lot of respect for those guys as musicians and as a group,” Cummins says. “There’s certainly a lot of philosophical things that are similar as far as how we approach music, but the end result is definitely something that’s a completely different beast at this point. And that’s what we always wanted — we wanted to be ourselves.”

The group originated as a college band at Notre Dame before relocating to Chicago, and has survived in part because of its close relationships. But the latest evolution among band members has included marriages, offspring, and for the first time, geographic dispersal.

Will this change in perspective affect the band’s future trajectory?

“I’m at a point now where if we didn’t grow at all and we stayed right where we are for the next 10 years, I’d be totally cool with that,” guitarist Brendan Bayliss says, calling from the security line at Chicago’s Midway Airport. “There’s a part of you that wants to grow and play in front of new people and bigger crowds, but it’s not the end-all, be-all. A year or two ago it meant more to me. I don’t know if having a kid changed my perspective on life, but it’s just not as much of a concern of mine.”

For his part, Cummins sees a continued rate of steady growth for the band. “I don’t see why things couldn’t keep going in the right direction. As long as we keep that trend of slow and steady, I’m happy with that.”

Bayliss says the group’s ability to pull off its highest-profile events depends on an enduring work ethic. “It’s the final exam that you have to study for, and then take it. Those are kind of high-anxiety things because we set it up, really, to make everybody that we play for all the time the happiest.”

The band still rehearses about an hour every day when on the road, working through deep cuts or song transitions planned for that night’s show. Onstage, spontaneity is prized, but intra-band communication is explicit: hand signals, or even a step forward or backward, might cue a change in direction.

That sort of discipline, tinged with whimsy, is also seen in the way Umphrey’s McGee handles its career. About every three years or so, its members—guitarist Jake Cinninger, percussionist Andy Farag, drummer Kris Myers and bassist Ryan Stasik, in addition to Bayliss and Cummins — assemble for a formal confab on the state of the band.

Frequently in touch with fans, Cummins is the most active band member on Twitter, sometimes announcing tour dates there or soliciting requests for upcoming shows. But not every request of the most hardcore fans can be honored.

“The fans on Twitter are always asking me for the craziest stuff,” he says. “The other day I had to ask if anybody had any reasonable requests.”

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